Question

运行以下功能时：

def RestoreSelection(self, selectedItems):
    self.RecvList.selection_clear(0,"end")
    items = self.RecvList.get(0,"end")
    for item in selectedItems:
        for _i in items:
         if item[:6] == _i[:6]:
            index = items.index(item)
            print index
            self.RecvList.selection_set(index)

我收到此错误：

Exception in Tkinter callback
Traceback (most recent call last):
  File "/usr/lib/python2.7/lib-tk/Tkinter.py", line 1437, in __call__
    return self.func(*args)
  File "/usr/lib/python2.7/lib-tk/Tkinter.py", line 498, in callit
    func(*args)
  File "./pycan1.8.py", line 710, in RecvBtn_Click
    self.RestoreSelection(selected)
  File "./pycan1.8.py", line 443, in RestoreSelection
    index = items.index(item)
ValueError: tuple.index(x): x not in tuple

不幸的是，错误消息并不十分清楚。有人可以解释这个错误信息是什么？是什么导致函数产生它。

这只发生在我将嵌套的for循环放入。

Answer 1

这意味着您在items元组中尝试查找的索引值在此元组中不存在。

>>> a = (1,2)
>>> a.index(3)
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
ValueError: tuple.index(x): x not in tuple

为了避免这种情况，你可以在你试图获取try\except块的索引的地方包装行，例如：

def RestoreSelection(self, selectedItems):
    self.RecvList.selection_clear(0,"end")
    items = self.RecvList.get(0,"end")
    for item in selectedItems:
        for _i in items:
         if item[:6] == _i[:6]:
            try:
                index = items.index(item)
            except ValueError:
                index = None #set default value here
            print index
            self.RecvList.selection_set(index)

验证导致错误

1 个答案: